#define _CRT_SECURE_NO_WARNINGS 1
#include<iostream>
using namespace std;
const int N = 5010;
int f[N][N];
int a[N][N];
int n, m;
int main()
{
    cin >> n >> m;
    while (n--)
    {
        int x, y, v;
        cin >> x >> y >> v;
        x++;
        y++;
        a[x][y] += v;
    }
    n = 5001;
    for (int i = 1; i <= n; i++)
    {
        for (int j = 1; j <= n; j++)
        {
            f[i][j] = f[i - 1][j] + f[i][j - 1] - f[i - 1][j - 1] + a[i][j];
        }
    }
    m = min(m, n);
    int ret = 0;
    for (int x2 = m; x2 <= n; x2++)
    {
        for (int y2 = m; y2 <= n; y2++)
        {
            int x1 = x2 - m + 1;
            int y1 = y2 - m + 1;
            ret = max(ret, f[x2][y2] - f[x1 - 1][y2] - f[x2][y1 - 1] + f[x1 - 1][y1 - 1]);
        }
    }
    cout << ret << endl;
    return 0;
}